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Georgia 

State Board of Entomology 

E. LEE WORSHAM, State Entomologist 



BULLETIN No. 49 



JANUARY, 1918 



PECAN INSECTS 

WILUAM F. TURNER. 

PECAN SCAB 

C. S. SPOONER. 

PECAN DISEASES OTHER THAN SCAB 

C. G. CRITTENDEN. 




Atlanta, 






Georgia 



Georgia 

State Board of Entomology 

E. LEE WORSHAM, State Entomologist 
BULLETIN No. 49 JANUARY, 1918 



PECAN INSECTS 

WILLIAM F. TURNER. 

PECAN SCAB 

C. 6. SPOONEB. 

PECAN DISEASES OTHER THAN SCAB 

C. G. CRITTENDEN. 






Atlanta, 



Georgia 



'^\ i 



GEORGIA STATE BOARD OF ENTOMOLOGY. 



ORGANIZATION. 

HON. J. J. BROWN, 
Chairman, Commissioner of Agriculture, Atlanta. 

HON. R. C. BERCKMANS, 
Augusta. 

HON. JNO. A. COBB, 

Americus. 

E. LEE WORSHAM, 
State Entomologist and Secretary of the Board, Atlanta. 

A. C. LEWIS, , 
Assistant State Entomologist, Atlanta. 

AV. V. REED, ^ ■ 

Assistant Entomologist, Atlanta. 

. W. W. CHASE, 
Assistant Entomologist, Atlanta. 

W. F. TURNER, 
Assistant Entomologist, Thomasville. 

IRA W. WILLIAMS, 
Cotton Specialist, Atlanta. 

C. A. McLENDON, 

Expert in Cotton Breeding, Atlanta. 
In Exchange 
Univ, of Illinois 

AUG 2 193* 



CONTENTS. 



FOREWORD 4 

PECAN INSECTS (William F. Turner)— 

Pecan Leaf Case-bearer 6 

Pecan Nut Case-bearer 14 

Cigar Case-bearer ^ 19 

Bu'dworm 21 

Shuckworm 22 

Fall Webworni 24 

Walnut or Pecan Caterpillar 25 

Catoealas 26 

Twig Girdler 26 

Flat Headed Borers 27 

Cossid Borer 28 

Shot Hole and Pin Hole Borers' 30 

Lesser Pecan Tree Borer '_ 31 

Curculio 32 

Hickory and Pecan Weevils 33 

Leaf-Feeding Beetles 34 

Leaf Hopper 35 

Pecan Phylloxera 35 

Pecan Aphis 36 

Spittle Insects 37 

PECAN SCAB (C. S. Spooner) 38 

PECAN DISEASES OTHER THAN SCAB (C. G. Crittenden)— 

Pecan Rosette 44 

Brown Leaf Spot 45 

Kernel Spot ^ ^ 46 

Nursery Blight 47 

Anthracnose , 48 

Crown Gall . 48 

Mildew 48 



FOREWORD. 



Pecan growing is rapidly becoming one of the most important in- 
dustries of south Geoigia and in recent j'^ears more and more plant- 
ings have been made in the central and even northern portions of 
the state. At present thousands of acres have been set out to pecans 
through south Georgia and these plantings are being increased 
yearly. (Frontispiece.) As a result the growers are already deeply 
interested in the insects and diseases Avhich attack the pecan, and 
these pests are of continually increasing importance as the capital 
which is invested in the business increases. 

The present bulletin is not intended to give exhaustive reports 
on the life histories of the various insects and diseases which attack 
the pecan. In fact, workers have been engaged in the study of the 
insects for such a short time that there are very few of them whose 
life liistories are thoroughly known yet. This is also true, though 
perhaps in less degree, of the diseases. 

In view of the numerous requests which are constantly being 
received for information concerning these matters, it was felt that 
the situation could best be met by a publication giving a general 
survey of the field. In the present bulletin, therefore, an attempt 
has been made to furnish the pecan growers with a guide by which 
they may become familiar with the insects and diseases Avhich are 
now injurious, or which may become so, and may further become fa- 
miliar with the principal methods of control. 

It should be borne in mind that, altho many insects are dealt with 
in this bulletin, probably only a few of them will ultimately be 
looked upon as serious pests of the pecan. In this connection it is 
well to call to mind that man}- fruits, for instance apples, have as 
many or even more species of insects attacking them. Yet under or- 
dinary conditions the grower has to contend with not more than three 
or four. Without doubt this will ultimatel}- be found to be the case 
with the pecan, also. Those insects Avhich are most injurious at 
the present time have been indicated, as have those which seem to 
possess habits and characteristics which may cause them to become 
of serious importance later. 

With regard to some insects, at least, it has already been proven 
that successful, commercial pecan culture must include tlie spraying 



of the trees. At first this seems a big item— something special which 
must be done. If the grower, however, will simply include spray- 
ing in his list of the year's operations, expecting to spray his trees 
at a certain time, just as he expects to plow at given periods, he 
will soon find that the matter adjusts itself naturally, and quickly 
becomes as little of a bug-bear as is planting or cultivating. 
All dates given in this bulletin are for Thomasville, Ga. 



PECAN INSECTS.* 

PECAN LEAT CASE-BEAEEE. 

{Acroiasis neiulella Eiley.) 

This insect is, at ilie present time, one of the most serious ene- 
mies of the pecan, probably causing more damage, in Georgia, than 
all other insects together. Fortunately, the species is, thus far, con- 
fined to south Georgia. It is present in injurious numbers about 
Thomasville, Cairo, Valdosta, Fitzgerald, Blackshear and Nashville. 
It has not been found in any numbers in the Albany district, how- 
ever, and we have no reports of it from central Georgia. Since it 
has already been present in Florida and south Georgia for several 
years we have abundant grounds for hope that it will not become of 
serious importance in regions north of those in which it occurs at 
the present time, yet so many other insects have demonstrated their 
ability to adjust themselves to unfavorable conditions, particularly 
of climate, that it is possible the Pecan Case-bearer may do so event- 
ually, and become a pest in portions of the pecan belt where it does 
not occur at present. 

The principal damage is caused in the spring. The insects be- 
come active at the time when the buds begin to burst. The cater- 
pillars or "worms" feed voraciously on the opening buds and ten- 
der shoots, frequently boring into and killing them. Young trees 
are often stripped entirely and, in bad outbreaks, trees as old as 12 
and 13 years maj^ be defoliated. This defoliation checks the growth 
of the trees and destroys the crop for the year. Since the larvae 
also attack the stems which bear- nuts the crop is frequently de- 
stroyed even when the damage to the trees is not particularly se- 
vere.f Later, when the trees are well leafed out and the larvae 
can no longer feed on buds and young shoots, they attack the 
bases of the main leaf stalks and the leaflets themselves. This 
feeding is not as serious as that done earlier in the season. 

*As indicated in footnotes, the portions on tliree or four of the insects were 
written by Mr. C. S. Spooner, formerly with the State Board of Entomology. 

t Still a third type of injury was noted on one variety of trees, the Young-, in 
the spring of 1916. Two trees about 30 ft. in height were under observation. Par- 
ticular notes were made on April 22nd. On these two trees practically all the cat- 
kins, or male blooms, w^ere destroyed by the worms, which fed at the base ol these 
catkins. Very little injury of any other sort was noticed on these two trees. On 
trees of other varieties, near the two trees in question, little or no injury to the 
catkins was observed but the larvae were feeding, as is their usual habit, at the 
bases of the main leaf stalk and on the leaves themselves. The crop of these two 
trees was a failure. 



LIFE HISTORY AND HABITS. 

The adult insect is a mottled grey moth which, when its wings 
are spread, measures about five-eighths of an inch, across. (Plate I, 
fig. 1.) When at rest it has a ha:bit of sitting on a small twig with 
its head raised, the body forming an angle of about 30° with the 
twig and this position, together with the coloring, makes it very 
difficult to see. (See cover.) It seldom flies during the day time, 
but is very active at night. 

Egg laying commences about the first of June and a few moths 
may lay as late as the first of August. The majority of the eggs are 
laid from about the middle of June to about the end of the first week 
in July. These eggs are small, soft, semi-transparent objects and 
are laid, almost invariably, along the main rib, on the under side 
of the leaf. In rare cases they are laid in angles between the side 
veins and one of the largest of the veins which branch off from 
these. We have never found eggs anywhere except on the under 
surface of the leaves. 

The eggs hatch in a few days. This hatching commences, at 
Thomasville, about the middle of June and continues into early 
August. Most of the eggs hatch, however, during the first three 
weeks in July. 

The young larvae, or "worms," are very small and usually red- 
dish brown in color. They immediately commence feeding, eating 
only the lower surface of the leaf. From the frass and excrement 
they form a little tube, spinning silk with which to bind the parti- 
cles together and line the case. This case is attached quite firmly 
to the leaf and runs along on the under surface of it. Commencing 
at the spot where the egg was laid the larva feeds outward, work- 
ing back and forth so that the spot is fan shaped. The upper sur- 
face of the leaf turns brown. As the larva feeds it builds its case out- 
ward. The case itself is very firmly and tightly made, but at the outer 
end the larva builds a loose fan-shaped tent, under which it feeds. As 
soon as it eats all the green which it can reach from this tent it 
draws the back portion of it together, prolonging the case, or tube, 
and extends the outer portion in such a manner as to cover more 
.green leaf. Since it also moves back and forth across the edge 
of the spot on which it has fed the case is curved, S-fashion, and 



finally, by fall, becomes very serpentine in form. (Plate II, fig. 2.) 
From one to twenty or more eggs may be laid on a single leaf. 
Each larva consumes only a small portion of the surface, usually 
Remaining between the side rib near which the egg was laid, and 
the next one toward the tip. A larva may cross one of these side 
ribs, however, and while it usually feeds outward toward the tip, 
an occasional worm will turn back toward the base of the leaf. 
The feeding spots are very noticeable from both the upper -and 
lower surfaces and in cases of severe outbreaks infested trees can 
be picked out from a considerable distance. Some of the larvae 
die during the summer, especially when there are several eggs laid 
on one leaf. Such larvae can always be located during the late 
summer and early fall, from the fact that the feeding spot is small 
and the end of the case does not reach to the edge of the brown 
spot. The tent usually is missing or the case may have been 
broken off entirely. 

This summer feeding of the larvae is not particularly serious, in 
itself, except in the case of very severe outbreaks on young trees, 
when the growth of the trees is checked somewhat. As has been 
said, each worm does not eat very much and since the leaves are 
hard and do not furnish much nourishment, especially toward the 
end of the summer, the larva grows very slowly indeed, being only 
about one-twentieth of an inch long when it is obliged to cease 
feeding in the fall. The importance of this period lies in the fact 
that, up to the present, we have found' it the best time to control 
the insect, as will be shown later. 

In the fall, shortly before the leaves drop, the little worms leave 
their cases and crawl down to the buds. Here they form tiny, 
round, flattened cases, called hibernacula, and in these they spend 
the winter. (Plate II, fig. 1.) The hibernacula are most fre- 
quently located in the little groove where the bud touches the twig. 
When abundant, however, they may be anywhere about the bud, or 
even on it. As has been intimated, there is a close connection 
between the time of this migration and the time when the leaves 
drop. At Thomasville, in 1916, the migration began late in Sep- 
tember and continued till frost, on November 16th. On October 
24th, observations showed that about 50% of the insects had left the 
leaves. The migration commenced earlier on Mobiles than on any 



FRONTISPIECE. 













Map showing the distribution of pecans, by counties. Each dot 
represents 100 trees. The actual distribution of the trees in each 
county is not shown. (Figures from the 19th Ann. Rept. of the 
State Entomologist.) 




rLAT^ L 





Fig. 1. Leaf Case-Bearer. 



Fig. 2. Nut Case-Bearer. 




FiT. 3. Cossid moth. 





Fig. 4. Bud worm. 



Fig. R Fall web-worm. 



Adults of some Pecan Insects. (Slightly enlarged.) 



PLATE II. 




Fig. 1. Pecan Case-Bearer. Win- 
ter cases on bud. (Enlarged.) 



Fig. 2. Pecan Case-Bearer. Sum- 
mer cases. (July 15.) (Enlarged.) 




Pig. 3. Pecan Case-Bearer. Spring cases on 
main leaf stalk. (Natural size.) 



PLATE III. 




Fig. 1. Pecan Leaf Case-Bearer. Late spring feeding. 




Fig. 2. Pecan Leaf Case-Bearer. Early spring feeding on opening buds. 



9 

other variety, Mobiles shedding their leaves before the other com- 
mon varieties do. Thus, on October 1, 1916, many hibernacula 
were found about the buds of the Mobiles, while none were found 
on other varieties. 

The little larvae spend the winter in the cases on the buds, 
only leaving them in the spring at about the time the buds begin 
to burst. They then commence feeding on the opening buds and 
tender shoots, often boring into them. (Plate III, fig. 2.) A new 
type of case is now formed, this being the case most commonly 
noticed by the growers. It is cylindrical, open at both ends, and 
is carried about by the worm, as it moves from place to place, al- 
ways standing out from the surface on which the worm is feeding. 
The young larva sometimes leaves one case entirely, building a 
new one in another location. When the larva bores into a shoot 
it usually fastens the case at the entrance of its burrow with silk, 
sometimes feeding with part of its body in the case and part in the 
burrow, at other times with its body entirely inside the burrow. 
At first the color of the case is a dirty grey, most of the outside 
being composed of frass. Later, when the larva is nearly full grown, 
more silk is used on the outside till finally the case is a light, sil- 
very grey in color. It is always lined with silk. These mature 
cases are nearly always found out on the leaf stalk or on the 
under side of one of the leaflets themselves. (Plate II, fig. 3.) 

The worms grow very rapidly at this time, becoming, when 
full grown, about three-fourths of an inch in length, while the 
case is about one inch long. The larva varies from a reddish 
green to olive green, the color depending somewhat on the por- 
tion of the tree on which the worm has been feeding. 

When the larva is full grown and ready to pupate, it almost 
invariably fastens its case on the main stalk of a leaf, between two 
leaflets. These it draws together, fastening them loosely to the 
case and to each other with silk. It then builds two silken flaps, 
or lips, at the outer end of the ease. These press together in such 
a manner that they cannot easily be opened from the outside, since 
any pressure simply closes them more tightly. On the other hand a 
very slight pressure from within will open them easily. 

The larva now rests in its case for a few days and then pupates, 
with its head toward the outer end of the case. This pupal stage, 



10 

the period during which it transforms from a worm to a moth, lasts 
on the average for about 16 or 17 days. In 1914, the period lasted, in 
two cases, only 14 days, while one insect required as much as 20. 
This pupal period commences about the middle of May, a few 
insects probably pupating even earlier. It continues as late as the 
first of July. At the end of this period the moths emerge and are 
soon ready to lay the eggs for another generation. 

CONTBOIi. 

Up to the present time the only successful method which has 
been discovered for controlling this pest is to spray the trees with 
arsenate of lead between the middle of August and the last of 
September. All attempts to control with arsenate of lead in the 
spring have failed. This is also true of efforts to kill the worms in 
the winter cases by spraying during the winter with lime-sulphur. 

The formula which we would now recommend is as follows.: 

Arsenate of lead (powdered)* 1 lb. 

Lime 2 lbs. 

Fish oil soap 2 lbs. 

Water 50 gals. 

The lime is added to this mixture in order to prevent the ar- 
senate from burning the foliage. "When it is not used the trees 
may be quite seriously injured. The soap is not absolutely nec- 
essary but its presence makes the spray mixture spread much more 
readily and evenly and, during the season of 1916, it was found 
that mixtures which contained the soap adhered to the foliage 
somewhat better than did those without it. 

In groves of young trees, up to five or six years of age, an or- 
dinary barrel pump may be used. In the older groves, however, 
the most satisfactory results can only be obtained by the use of a 
power sprayer. (Plate IV, figs. 1 and 2.) 

The most important point to remember is that the trees must be 
thoroughly sprayed. While it requires only a very minute quan- 
tity of the poison to kill the tiny worm it is absolutely essential that 
that poison shall be placed where the worm will reach it. Therefore, 
for good re sults, care must be taken that, in so far as is possible, the 

*If arsenate of lead paste is used, the amount must be doubled; that is, 2 lbs. to 
50 gals, of water. 



11 

under side of every leaf is covered with the material. If this is 
done the grower will have no trouble in controlling this pest. 

WINTER SPRAY. 

Growers frequently ask why winter spraying cannot be em- 
ployed against this pest. Several experiments have been con- 
ducted in which the trees were sprayed with lime-sulphur, and 
during the winter of 1916-17 we made extensive tests, using lime- 
sulphur, miscible oils and home-made oil emulsions. These sprays 
were absolute failures. The same was true of sprays containing 
nicotine sulphate and soap, applied in the spring just at the time 
the larvae were leaving their winter cases to commence feeding 
on the buds. Apparently the hibernacula are so tightly woven 
that the spray materials do not penetrate them thoroughly. The 
failure of the spring treatment to produce any appreciable effect 
seems to be due to the fact that no one time can be selected when 
a large enough percentage of the "worms" are exposed to the poison. 

NATURAL ENEMIES. 

There are several natural enemies which aid in controlling the 
Leaf Case-bearer. These consist of parasites, including several 
species ef minute wasps,* and at least one fly;t predaceous ene- 
mies, including two or three species of bugs which attack the larvae 
and suck out the juices; and birds, as blue jays, which tear open 
the cases and pick out the "worms." 

Rather limited examinations in one grove, during the season of 
1916, gave the following results: 8.7% of the larvae in the cases 
collected were destroyed by parasites; 12% had been killed by 
birds, while 14.2% were "sick." Some of these "sick" larvae may 
have contained parasites but this point was not definitely settled. 

In 1917, several- lots of cases were collected from five groves 
at various intervals between May 18th and July 27th. These 
were examined carefully and the results are recorded in the fol- 
lowing table : 

•Habrobracon variabilis Cush.. Macrocentrus sp., Exochus apicalis Cr. Several 
other species were reared in 1917, but these have not yet been determined. 
tExorista pyste Wlk. 



12 



Table 1— Percentage of Worms Killed by Natural Causes. 





Total 
Cases 


Parasites 


Killed by Birds 
No. % 


Dead & Dried 


Total Dead 


Grove 


No. % 


No. 


% 


No. 


%■ 


I 


304 


27 • 


8.8 


5 


1.6 


9 


2.9 


41 


13.4 


II 


365 


24 


6.5 


8 


2.2 


15 


4.1 


47 


12.9 


III 


614 


18 


2.9 


12 


1.9 


27 


4.4 


57 ■ 


' 9.2 


IV 


90 


15 


16.6 


4 


4.4 


4 


4.4 


23 


25.5 


V 


50 


7 
91 


14.0 


2 


4.0 


1 


2.0 


10 


20.0 


Ttl. 


1423 




31 




56 




178 




Avg. 






6.4 




2.1 




3.9 


12.5 



In view of the fact that extensive examinations, including sev- 
eral thousand individuals, have shown that there may be a total 
annual mortality of nearly 95% of this species, due mainly to the 
fact that large numbers never form eases on the buds, while many 
also die during the winter, and that in spite of this the species 
caused severe injury to the very groves in which the data was 
obtained, it is evident that little can be hoped for in the way of 
control by either parasites or birds. 

Some very interesting data were obtained during the past sea- 
son on the value oi a predaceous bug, Arilus cristatus, in the con- 
trol of the Leaf Case-bearer. Three bugs ate a total of 76 
"worms" between May 11th and June 5th. At this latter date 
other food had to be provided since no more Case-bearer larvae 
were available. The larvae were removed from their cases before 
being fed to the bugs, so these figures must be considerably in 
excess of those actually obtaining in the field, where the bugs are 
obliged to search for the "worms" and to attack them in their 
cases. They indicate, however, that this species may be of con- 
siderable benefit wherever it occurs in any numbers. As with the 
parasites and birds, however, predaceous bugs cannot be relied on 
to control the pest and wherever Case-bearers are abundant arti- 
ficial means of control must be employed. 



13 

VARIETIES OF PECANS ATTACKED. 
C. S. SPOONER. 

There is another most interesting point in connection with this 
insect and that is the freedom from attack enjoyed by many varie- 
ties of pecans. This is very evident and easily observed. In the 
same grove with trees of different varieties planted next each other, 
the one will be heavily infested and the other almost free from 
attack. 

It was first noticed that the large leaved varieties were most 
subject to attack, while the small leaved varieties were, to a large 
extent, free from the insects. Further examinations showed the 
probable reason for this. It will be remembered that the eggs of 
this insect are laid in the angles made by the secondary veins with 
the midrib. Now in the large leaved varieties the veins are also 
large and form a deep pocket at this angle. In many cases the 
entrance to this pocket is hidden by hairs. This forms an ideal 
place for the eggs of the Case-bearer. They are hidden and pro- 
tected from weather. The small leaved varieties lack these pockets 
and the egg must be laid directly on the surface of the leaf. There 
is little doubt but that the presence of this pocket favors the at- 
tack of these insects. The moths would search for them in prefer- 
ence to depositing their eggs on the small leaved varieties. 

Notes were taken on the numbers of Case-bearers found on the 
different varieties. Trees in the same groves were compared and the 
insects were there in sufficient numbers to seriously infest all the 
trees, had they not selected the varieties most suitable to them. 
The following varieties were severely infested : 

Capitol, ^ Frotscher, 

Van Deman, Taylor, 

Schley, Alley, 

Nelson, Appomattox, 

Stuart, Delmas. 

The following list had very few of the Case-bearers on them: 

Money-maker, Mantura, 

Hassen, Hican (none), 

Georgia, Teche, 

Curtis, Young. 

Russell, 



14 

The following varieties seemed to be intermediate between the 
above two groups: 

Mobile, Senator, 

Creole, Teddy, 

Success, Bacon, 

President, Hadley. 

Pabst, 
These lists do not by any means include all the varieties, but 
are simply those which have been under observation. 

The question may arise as to whether freedom from the at- 
tack of this insect .should be considered in selecting varieties for 
planting. In cases where the varieties are about equal in other 
desirable points it would be well to let this point influence your 
choice. This insect is, however, so readily controlled that the free- 
dom from attack would not outweigh any serious faults in a va- 
riety. 

PECAN NUT CASE-BEARER. 

(Acrobasis liebescella Hulst.) 

The Pecan Nut Case-bearer is a comparatively recent comer to 
Georgia, having been here for probably only four years, or five 
at the most. It has been in Florida for a somewhat longer period 
and is of quite common occurrence west of the Mississippi, where it 
appears to be native. As far as we know, in Georgia the species 
is now confined to groves about Thomasville and Cairo, though it 
may occur elsewhere along the southern edge of the state. This in- 
sect, as its name indicates, is particularly an enemy of the nuts, 
themselves, altho in certain stages it attacks the shoots and swollen 
bases of the leaf petioles. 

While the Nut Case-bearer is not of great economic importance 
in Georgia at present, because of its very limited occurrence, it 
seems very possible that it may eventually become our most se- 
rious pecan enemy. In one grove near Thomasville, during' 1916, 
the worms destroyed 50% of the crop on the Frotscher trees and 
over 35% of the Teche before June 20th. The species always 
causes most of its damage early in the season, as will be explained 
later, but the total damage to the grove for the year was un- 
doubtedly as much as 50%, including both varieties. 



15 



LIFE HISTORY AND HABITS. 



Unlike the Leaf Case-bearer, this species has three generations 
during a single year. It spends the winter as larvae in hiber- 
nacula attached to the buds, just as does the Leaf Case-bearer, 
The larvae, or "worms," leave these winter cases as soon as the tree 
commences growth in the spring, and complete their growth by 
boring into the new shoots and feeding within them. The larvae 
look very much like those of the Leaf Case-bearer, varying in color 
from a yellowish brown through various shades of greenish brown 
and greenish grey to a pinkish olive green. The head and tho- 
rasic shield are dark brown. These larvae become full grown and 
pupate about the first of May and the moths begin to emerge and 
lay eggs about the middle of the month, at Thomasville. 

The moths are about the size of the Leaf Case-bearer moths. 
Their fore wings are darker in color with a ridge of black scales 
at the base of each wing. When the wings are folded these ridges 
give the moth a hump-backed appearance. The hind wings are 
lighter grey. The abdomen is grey while the head and thorax 
have a more brownish cast. (Plate I, fig. 2.) 

The eggs, which are very small and greenish or pinkish white 
in color, are laid at the blossom end of the newly formed nutlets, 
which at this time are about one-fourth to one-half of an inch in 
length, depending on the variety. These eggs hatch in a very 
few days and the tiny "worms" crawl down to the bases of the 
nutlets and bore into them, usually close to the line where the 
nut is attached to the stem, although occasionally entrance holes 
are found elsewhere on the nuts. 

The young worm usually hollows out the nutlet ifi which it is 
feeding, eating out the portion which would later become the nut 
and leaving the portion which would eventually become the husk. 
Having finished one nutlet it leaves it and attacks another in the 
same cluster. Occasionally the larva migrates to a second nut be- 
fore it has eaten very much in the first. One larva may feed on as 
many as four or five nuts before reaching its full size and it is for 
this reason that the damage is so severe at this time of the year. 
The hollowed nutlets soon turn brown and dry and may be seen 
hanging from the stems by threads of silk used by the worms in 



16 

making their cases. These empty nuts frequently hang on the 
trees throughout the season. 

After becoming half grown, or even sooner, the larva usually 
builds a short tube or case, perhaps one-sixteenth to one-eighth 
of an inch in length, about its entrance hole. (Plate V, fig. 1.) 
This is formed of silk and frass. Frequently a worm will also 
build a tube from the base of the nut on which it has been feed- 
ing to the base of the next one which it attacks and these tubes 
may be one-half an inch or more in length. This habit, together 
with its feeding habits, suggested the name of Pecan Nut Case- 
bearer.* 

In the laboratory the first larva reached full size, in 1916, about 
June 6th, and one had pupated by June 9th. The great majority 
of the insects had pupated by June 24th. The larva when pre- 
paring for this stage faces with its head towards the entrance bur- 
row and transforms within the little nut which is just about large 
enough to hold the pupa. The moth emerges through the entrance 
burrow, which is of good size. This is due to the fact that the in- 
sect pupates, of course, in the last nut attacked and that the 
"worm" was nearly grown when it entered this nut. 

The first adult emerged, in the breeding cage, on June 18th in 
1916. In 1917 moths appeared as early as June 10th. Emergence 
continued till July 9th, 1916, and to July 12th, 1917. 

These moths, in turn, lay eggs at the blossom ends of the nuts, 
which are much larger now, being fully half or more than half 
grown. Each "worm" feeds only in one nut, and does not clean 
that one out. As a result each larva of this generation destroys 
only about one-fourth as many nuts as does a larva of the first 
generation. (Plate V, fig. 2.) 

The entrance burrow is still made near the base of the nut. 
Since it is made by the worm just after it has hatched it is usually 
very small and in many instances there is no case about it. Also the 
adult frequently cannot emerge through it and consequently in 
such cases another method for emergence is provided. Before it 
pupates, the larva eats a hole almost through the husk of the nut, 
leaving just a thin layer of the surface, to cover it. This hole is 
usually in the side of the nut near the base. The larva then forms 

*This name was suggested by Mr. A. C. Gill, of the U. S. Bureau of Entomology. 



PLATE IF. 




Pig. 1. Spraying for Case-Bearer. Using a Bordeaux Nozzle on one line, 
so that the tower is not needed. 




Fig. 2. Pilling tank from a well, by means of a barrel. 



PLATE V. 




Fig. 1. Work of first generation on small nuts. 
(Much enlarged.) 




Fig. 2. Work of second generation on nearly 
grown nuts. (Slightly enlarged.) 



M 



PLATE VI. 




Fig. 1. aunimer case 
(much enlarged). 




Fig. 2. Winter case 
near bud. 




Fig. 3. Summer case on leaf; note dark 
area, where insect has fed. 



Cigar Case-Bearer. 



PLATE III. 




Fig. 



1. Web-worm moth 
covering eggs. 



Fig. 



Same e^s hatch with 
moth removed. 




Fig. 3. Egg batch of wahiut, or pecan, catcrijilkir. 



17 

a cocoon of silk and frass, with the head end open and attached 
about the exit hole. It pupates in this cocoon and later trans- 
forms into a moth. This moth simply pushes out the flap and 
escapes. 

The nuts attacked by the second generation seldom hang on 
the trees as do the nuts attacked by the first, since they are much 
heavier and are not held by silk. They frequently drop before 
the moths have emerged, and the worms complete their feeding 
and transform to adults in these nuts on the ground. 

The second generation pupated between August 3rd and 20th, 
1916, mostly about August 16th. Moths began emerging about 
August 15th and apparently all had emerged by about September 
1st. In 1917 one moth emerged as early as August 10th. 

The larvae of the third generation feed little, if at all, on the 
nuts. Instead they attack the swollen bases of the leaf stems, 
feeding in these until it is time for them to form their winter 
cases on the buds. It will be noticed that the 'Svorms" of this 
generation feed on leaf and stem tissue throughout their entire 
life (both in the fall and spring), while those of the other two 
generations feed on nuts. 

CONTROL. 

We have not conducted any experiments, as yet, for the par- 
ticular control of this species, for this reason. During 1916 one 
grove, rather severely infested with Leaf Case-bearers, was sprayed 
as recommended, with arsenate of lead, between August 22nd 
and 25th. In 1916 fully 50% of the nuts in this grove were de- 
stroyed by the Nut Case-bearer. In 1917 this species destroyed 
only 5.8% of the nuts on the worst infested tree in the grove. 
These results seem to indicate that the spray used for the Leaf 
Case-bearer, if applied at the proper season, will also control the 
Nut Case-bearer. However, this cannot be definitely stated, since 
another factor, to be mentioned below, complicates the situation 
and may be sufficient of itself to account for these results. This 
decrease in infestation further precluded the possibility of control 
experiments in 1917, as no groves were found in which the in- 
sects were present in sufficient numbers to furnish reliable data. 

As previously^ noted, winter spraying with various materials 



18 



has not yet proven efficient against the Leaf Case-bearer, and 
cannot be expected to be any more so against this insect. 



NATURAL ENEMIES. 

The natural enemies of this species appear to control it more 
efficiently than is the case with any other important insect at- 
tacking pecans. To return once more to the grove already men- 
tioned as losing half of its crop through the work of the Nut Case- 
bearer, during 1916, it was found that 50% of the first generation 
was destroyed by parasites. Of these there were reared two spe- 
cies of Hymenoptera,* which together killed 23.5%, and one Dip- 
teron,t or fly, which accounted for 26.5%. As will be seen, this 
is the most important of the enemies of the Nut Case-bearer as yet 
recorded. This fly also attacks the Leaf Case-bearer to some ex- 
tent. 

As a result of this parasitism the second generation was much 
less abundant than the first. The percentage of "worms" de- 
stroyed in this way was also less, in the second generation, but still 
about 10% to 12% were killed. This difference is probably due, 
for the most part, to the fact that the larvae of this generation 
live entirely in a sheltered position, while those of the first gen- 
eration are frequently exposed, when migrating from one nut to 
another and before they are able to burrow within each new nut, 
thus giving the fly, which is the most important enemy, an oppor- 
tunity to lay its eggs on them. 

In 1917, as stated in the discussion on control, the infestation 
in this same grove was only nominal, one tree, the most severely in- 
fested, losing only 5.8% of its nuts, and the damage to the entire 
grove being about 1%, or less. Since this grove was sprayed, in 1916, 
at about the time the young larvae began to attack the bases of the 
leaf stems, many of them may have been killed by the spray. Never- 
theless, the results for the early part of 1916 indicate that parasites 
exert an important influence on the abundance of Nut Case-bearers. 

In 1917, of the insects handled in breeding cages, 17.3% of the 
first generation were destroyed, 13% by the fly and 4.3% by the 

*Habrobracon variabilis Cush., Mlcrobracon sp. Other species reared In 1917 
have not been determined. 
tExorista pyste Wlk. 



19 

wasp parasites. As a result the second generation was not at all 
abundant, only an occasional infested nut being found. 

Growers should bear in mind the fact that parasites are al- 
most never entirely satisfactory as a means of control of in- 
jurious insects. They never absolutely destroy their host insect, 
as to do so would be to starve themselves to death. However, 
during years when the host insect is scarce, great numbers of the 
parasites cannot find food and consequently die. Thus they be- 
come scarce, in their turn, and the host insects being almost free 
from enemies begin to increase in numbers, rapidly, the parasites 
also becoming more numerous as their food insects become abun- 
dant, but never quite catching them. Finally there is a climax year 
when the pest is extremely abundant and injurious, at first, while 
the parasites are also abundant, and finally destroy a large per- 
centage of the injurious form. As a result the pest will be scarce 
the next year and the parasite, abundant at first, will themselves be- 
come more and more scarce as their food becomes harder and 
harder to find, till they too are rare, and the whole cycle begins 
over again. 

It is for this reason that insects having important insect ene- 
mies, such as is the case with army worms, are abundant only pe- 
riodically. This will undoubtedly prove true with the Nut Case- 
bearer and consequently it will probably be necessary to supple- 
ment the work of parasites by artificial control during some sea- 
sons. 

VARIETIES OF PECANS ATTACKED. 

Very little has been noted on this phase of the problem. In 
the spring of 1917, however, in a grove containing Frotscher, 
Teche and Alley, it was observed that a few infested nuts were 
to be found on almost every Frotscher before any could be located 
on Alley or Teche. Later, however, the two latter varieties were 
attacked slightly. 

THE CIGAE CASE-BEAEER. 

CColeophora caryaefoliella Clem.) 

This insect is a leaf feeder like the Leaf Case-bearer. It is a 
much smaller insect than the latter, the adult being a small, shiny 



20 

brown moth, which, with its wings spread, measures something 
under half an inch across. The wings are very narrow with a 
thick fringe of long hairs on the hind margins. The case is en- 
tirely different from that constructed by the two case-bearers which 
have already been discussed, in that the latter construct a case, 
bit by bit, from particles of frass bound together with silk, while 
the Cigar Case-bearer makes its case of pieces of leaf, fastened 
and lined with silk. (Plate VI, fig. 1.) 

While this insect is widely spread throughout the pecan belt of 
Georgia it has not been found, as yet, in sufficient numbers to cause 
serious damage. Infestations have been observed in Florida, how- 
ever, where the damage was very severe. 

The life history of the insect is very similar to that of the Pecan 
Case-bearer. The young larvae spend the winter in small cases 
around the buds, usually in the angle between the bud and the 
twig. (Plate VI, fig. 2.) In the spring, when the buds swell, they 
leave their nesting place and feed upon the buds, destroying them. 
Later they feed on the leaves. When feeding on the leaves the 
larva mines into the leaf, eating out the interior, but leaving the 
upper and under surface intact. In doing this it fastens its case 
at a right angle to the leaf and makes a small hole through the 
surface, directly under the mouth of the case. It then eats out 
the interior of the leaf in every direction, as far as it can reach. 
Having exhausted one spot it moves its case to a new place and 
repeats the operation. (Plate VI, fig. 3.) 

The insects pupate during the first part of May and the adults 
emerge the last of May and the first of June. The eggs are laid on 
the leaves, during the middle and latter part of June. Upon 
hatching the larvae mine into the leaves and spend some time 
there, entirely between the two surfaces. They then cut out the 
dry brown portions of the leaf, tie them together into a case and 
move about, feeding as previously described. In the fall they mi- 
grate from the leaves to the buds where they attach themselves for 
the winter. 

This insect seldom does sufficient damage to warrant control 
measures. In case of local severe outbreaks we would recommend 
spraying the trees with arsenate of lead, in the spring, using the 
formula given for the control of the Leaf Case-bearer. 



21 

THE PECAN BUDWOEM. 

(Proteopteryx bolliana Sling.) 

Altho it attacks trees of all ages to some extent, the budworm 
is particularly a pest of nursery trees and of trees newly set in 
groves. Like many other pests, while it occurs throughout the 
pecan growing region of Georgia, it very seldom is present in suf- 
ficient numbers to cause serious injury. 

This species spends the winter in the adult, or moth stage, hiding 
under loose bark or elsewhere about the fields. The moth is about 
the size of the Leaf Case-bearer moth, measuring about five-eighths 
of an inch with the wings spread. The general color of the front 
wings is grey mottled in a very pretty pattern with black, while 
the hind wings are dark grey without markings. (Plate I, fig. 4.) 
These moths are very abundant in the fall, especially during No- 
vember, when they may be found resting on the trunks and larger 
branches of the trees. If disturbed they fly only a short distance, 
perhaps four or five feet, returning immediately to the same tree. 

The larvae are greenish white in color, with black head and 
thorasic shield when young — these becoming dark brown in the 
older larvae. The full grown worm is about five-eighths of an inch 
long. These grown larvae of the first generation usually leave the 
bud and migrate to the trunks, where they pupate under loose 
bark. This habit seems to be very strongly ingrained, since in at 
least one instance under observation the larvae were forced to 
travel more than thirty feet from foliage to trunk, which they did in 
large numbers. 

There are at least five generations of this species in South Geor- 
gia. The later generations, not having the new and tender shoots 
to feed on, pick out the youngest foliage present on the trees. 
This is particularly noticeable during the late summer when the 
trees put on their second growth. At this time the work of these 
worms, which has been scarcely noticeable for two or three months, 
becomes very evident again. In feeding on the foliage the larva 
folds over the edge of the leaf, fastens this loosely with silk and 
feeds within, or at the ends of this fold. These larvae do not mi- 
grate to the trunk for pupation, as do those of the first generation, 
but transform within the folded leaflet. 



22 



CONTROL. 



Under ordinary conditions no control measures are required 
against this pest. In severe local outbreaks, however, it would 
be well to spray the trees with arsenate of lead in the spring. 

PECAN SHUCKWORM. 

{Laspeyresia (Enarmonia) caryana Fitch.) 

This insect occurs throughout the pecan belt of Georgia. While 
it is not found in injurious numbers in all localities, practically no 
grove in the state is entirely free from it, and it may become serious, 
during some seasons, wherever it occurs. 

The young, or larvae, burrow in the outer shucks, or husks, of 
the pecan nuts. The damage is of two sorts. If the insects at- 
tack the young nuts these fail to develop. If they attack the larger 
nuts they may fail to fill out, so that when gathered they contain 
merely a shriveled kernel. The principal injury to the large nuts, 
however, consists in staining the shell with dark blotches. This 
materially reduces the market value of nuts. Considerable trouble 
is caused also by the fact that the infested husks often stick to 
the nuts and must be removed by force. 

The life history of this species is not completely known, at 
present, but enough is known to suggest a sure method for sup- 
pressing the pest, as will be shown later. The larvae spend the 
winter in the shucks, on the ground. Toward spring, that is in the 
latter part of February and through March, they pupate, or go into 
the resting stage during which they change from the worm to the 
adult moth. This stage, also, occurs in the husk of the nut. The 
insects become adult and emerge from the husks early in the 
spring. A few have been reared as early as March 22d (1914) and 
emergence may continue at least as late as April 28th (1916). The 
time of greatest emergence was from April 7th to 14th in 1914, and 
from April 3d to 10th in 1916. The adult is a small moth about one- 
half to five-eighths of an inch across, when the wings are spread. 
The color is mottled brown and bronze. 

In the early spring, when the moths of the overwintered gener- 
ation appear, the nutlets have not yet been formed and the activ- 



23 

ities of this species during the weeks intervening between the 
emergence of the moths and the appearance of larvae in the young 
nuts have not been definitely determined. It had been thought 
that the larvae might attack the young shoots, but whether or 
not such is the case we have not been able to determine as yet.* 

Beginning in late June the larvae of this species are found at- 
tacking the nuts. These larvae are creamy white in color, with 
light brown heads. They feed on the husk, or shuck, of the nuts 
and during the early part of the season, before the nut shell is hard- 
ened, they frequently eat into the nut itself. Moths again appear 
in August. These lay eggs on the nuts or leaves and from these 
hatch out the worms found in the shucks at gathering time. These 
worms are not full grown when winter arrives but continue their 
feeding in the shucks on the ground till about midwinter or even 
later, when they pupate, as noted previously. 

CONTROL. 

The best method of control is to gather and burn the shucks 
when the nuts are harvested in the fall. This is an economical and 
very effective method of reducing the numbers of the pest. If 
the nuts are beaten from the trees on to large sheets, laid on the 
ground, the nuts can then be picked out and the shucks gathered 
and put into racks and carried off to be burned. In this way a 
very large per cent of the insects will be destroyed. 

Late fall plowing will also prove effective. Experiments have 
shown that 75 to 80% of the insects buried to a depth of three inches 
will be killed and over 95% of them killed when covered to a depth 
of six inches. Pasturing hogs in the groves during fall and winter 
will undoubtedly be beneficial, also. 

NATURAL ENEMIES. 

Parasites have been reared in considerable numbers from this 
insect, t The percentage of parasitism is often very high, altho 
there is no present indication that natural enemies will control the 
pest sufficiently to warrant stopping the artificial measures men- 
tioned abovCi 



•Gill states, in a recent bulletin, that these first generation larvae probably at- 
tack pig nuts and hickory nuts, for the most part, only a small percentage of the 
latest moths to emerge, waiting for pecan nuts. fGill, J. B., Farmer's Bulletin 843, 
U. S. D. A., 1917.) 

tCalllephlaltes graphollthas (Cres.), Phanerctoma tibial 's Hald., MIcrobracon sp. 



24 

THE FALL WEBWORM. 

(Hyphmitria cunea Drury.) 

This insect is well known to all pecan growers. It forms the 
familiar webs enclosing the tips of the branches. The adult moth 
is about an inch across when the wings are spread. These moths 
are usually pure white in color, although sometimes they are marked 
with black spots on the wings. (Plate I, fig. 5.) The eggs are laid 
in clusters of several hundred on the under side of the leaves. The 
moth usually covers the egg batch with her body and wings, re- 
maining in this position until she dies. (Plate VII, figs. 1 and 2.) 

Upon hatching the young caterpillars commence feeding upon 
the surface of the leaves and as they feed they enclose the foliage 
in a web. When they exhaust the food within the web they en- 
large it, including more and more leaves until the entire tip of 
the branch is covered, forming the unsightly nest with its en- 
closed brown and dead leaves which is such a familiar sight on 
many kinds of trees. The caterpillars are usually yellow and are 
clothed with long black and yellow hairs. Occasionally they are 
very dark, almost black in color. 

When fully grown the larvae leave the nests and crawl to some 
secluded spot, under loose bark, under boards and sometimes just 
below the surface of the soil. Here they pupate and later the moths 
emerge to lay eggs for the next generation. 

In southern Georgia there are two broods a year and a partial 
third brood. That is, some of the late caterpillars of the second 
brood do not mature the first season. The insect spends the win- 
ter in the pupal stage, the moths emerging in the spring. The first 
nests appear about the middle of May, the second brood nests ap- 
pearing in August and September, and the partial third brood also 
appearing late in September and into October. 

Aside from the unsightly appearance which the nests give the 
trees, this insect is not of serious importance during most years and 
in most localities, though its feeding is bound to check the growth 
of the trees to some extent. This is especially true in the case of 
the young groves and nursery stock. Occasionally, however, the 
damage is very serious, as in 1916, around Thomasville. During 
that year the species was abundant throughout the summer and by 



25 

tke middle of September several groves were almost defoliated. 
(Plate VIII, fig. 1.) Most of these groves were young ones, but 
one, composed of nine year old trees, was so severely attacked that 
by the end of September somewhat over 40% of the foliage of the 
entire grove had been eaten by the caterpillars. Of course this 
work was not evenly distributed, so that while a very few trees 
were not attacked, many were entirely defoliated. In addition 
to eating the foliage the caterpillars fed on the shucks of the nuts. 
As a result the shells were badly stained and it was practically im- 
possible to remove the uneaten portion of the shucks from the nuts, 
so that the crop on these trees was almost worthless. (Plate VIII, 
fig. 2.) 

CONTROL. 

Such outbreaks are entirely unnecessary if care is taken to de- 
stroy the caterpillars early in the season. This may be done by 
systematically destroying the webs with the worms in them. They 
can be burned with a torch, or cut off and burned later. Many peo- 
ple simply twist the nests out of the branch by means of a stick with 
a nail driven partly through one end, and then crush the larvae on 
the ground. With a little care in this matter the grower will have 
no trouble in controlling the pest. 

WALNUT OR PECAN CATERPILLAR. 

(Datana integerrima G. & R.) 

This is another leaf-eating insect which feeds upon the pecan. 
The larvae are dark with two white stripes on each side of the 
body, and are clothed with a few short hairs. The adult moths are 
yellow brown with four white stripes across each front wing. 

The eggs are laid in masses of several hundred on the under side 
of the leaves. (Plate VII, fig. 3.) The caterpillars feed on the 
foliage. Unlike the Fall Webworm these insects do not spin webs 
but move freely about the trees. When nearly grown the larvae all 
gather together on the trunk of the tree on which they are feeding 
and shed their skins for the last time. They then go back to the 
branches and feed for a short period after which they leave the 
tree and enter the ground to pupate. 



26 

These insects may be easily killed while they are in the bunch 
on the trunk of the tree. They can be scraped off and crushed. 
This will greatly reduce the numbers of future generations. In 
cases where the insect is very numerous the trees should be sprayed 
with arsenate of lead, II/2 pounds of powder or 3 pounds of paste 
to 50 gallons of water. 

THE PECAN CATOCAItAS. 

{Catocala spp.) 

At least two species of Catocalas feed on pecan. The adults 
are large moths, with greyish or dark brown front wings. The hind 
wings of one species are yellow with two transverse black lines, 
while those of the other are dark brown with a narrow band of 
white. 

The caterpillars, when full grown, are large, one measuring over 
two inches in length and the other three inches. Both are dark grey 
with various markings. The hide is tough and leathery in appear- 
ance, and the caterpillars are sometimes known as "alligator 
worms. ' ' 

These insects, because of their coloring and their habit of hiding 
in crevices in the bark during the day time, are seldom noticed. 
Ordinarily they are not particularly injurious but they may be- 
come so, occasionally. The larvae are usually present only in 
April and May. They may be controlled by hand picking or by 
an arsenical spray. They will also gather, at night, under bands of 
burlap, if these be tied loosely about the trunks, and can be col- 
lected and destroyed the following morning. 

TWia GIBDLEES. 

(Oncideres cingulata Say.) 

The twig girdlers are probably the most widely known of all 
the pecan pests and they occur throughout the pecan belt. There 
are two species, but the only one observed thus far, injuring the 
trees in this state, is cingulata. Both apparently work in the same 
manner. 



27 

The female beetles girdle the small branches of the trees and 
lay their eggs in these. The cut branches eventually break and fall 
to the ground. It is this pruning work which is known to the grow- 
ers, the beetles themselves seldom being seen. As has been said this 
girdling is done by the female, which lays its eggs in these cut twigs. 
The work starts about the middle of September and continues un- 
til December. The female, after girdling a twig, proceeds to lay 
eggs in the cut-off portion, from one to several eggs being depos- 
ited in a single twig. The beetle cuts a slit just below a bud, then 
thrusts her ovipositor through this slit between the wood and the 
bark and deposits a single long slender white egg. (Plate IX, fig. 
2.) She usually scars the bark with transverse shallow grooves, be- 
low the point where the egg is deposited. (Plate IX, fig. 1.) The 
purpose of this scarring is not certainly known. It probably aids 
in protecting the egg in some manner. There can be no doubt, on 
the other hand, that the girdling of the twig is for the purpose of 
killing it, since its continued growth would crush the eggs. Also, 
the young are probably unable to feed on live wood. 

The eggs hatch in a little less than a month and the white 
borers immediately commence feeding. This feeding continues 
through the winter and on till the next fall, the borers becoming full 
size and pupating in late August or early September. In some, 
cases it appears that the adults do not emerge the first year, but 
the pupae, or perhaps the larvae live over till the next year. 

Under ordinary circumstances the injury caused by these in- 
sects is not of serious importance. When very abundant, however, 
especially in young groves, the girdlers may cause very material 
damage. 

In order to control this species all the fallen twigs should be 
gathered during the fall and winter and burned. It is not possible 
to destroy the insects entirely as they also attack hickories and per- 
simmons, in the woods, where it is practically impossible to em- 
ploy this method. If followed faithfully, however, the grower 
will have no difficulty in keeping the girdlers well in hand. 

FLAT HEADED BORERS. 

The flat headed borers are the most abundant and most de- 
structive of the borers attacking the pecan. The adults of these 



28 

borers are flat, hard beetles usually shiny and with metallic lustre. 
The larvae are whitish grubs with broad flat heads, the body cyl- 
indrical and much narrower than the head. Three species have 
been taken from pecan,. thus far.* Of these the most important 
seems to be the Apple Tree Flat Headed Borer. 

The larvae bore into the bark and feed between the bark and 
the wood. As is well known this is the part of the tree which is 
alive and growing. So wherever these insects bore, that por- 
tion of -the tree is killed. On small trees or where the number of 
borers is large these tunnels may extend entirely around the tree, 
thus girdling and killing it outright. 

The adult beetles emerge principally during May and deposit 
eggs in crevices in the bark. As soon as these eggs hatch the larvae 
tunnel into the bark. When fully grown these larvae enclose them- 
selves in cells composed of borings and frass and there pupate. The 
following spring the adults emerge and lay eggs for the next gen- 
eration. 

Judging by evidence recently obtained there may either be two 
broods a year or it may sometimes require two years for the in- 
sects to mature. The fact that larvae of two sizes have been found 
in the fall leads to one of these conclusions.! 

The most satisfactory method of combating these insects so far 
known, is to dig them out. Their presence is usually indicated by 
cracks in the bark along a depressed or sunken area. The tunnels 
should be opened and then painted with a good quality of white 
lead paint to prevent further decay. 

THE COSSID BOEER. 

(Cossula magnifica Strecker.) 

This is the insect whose larval stage and work are referred to by 
growers as "round heads" and "round head work." These are not 
round headed borers, however, the adult of the round head being 
a hard-shelled beetle, with long antennae or "horns," much like the 
adult of the twig-girdler, while the adult of the cossid borer is 
a moth. (Plate I, fig. 3.) 

*Chrysobothrls femorata Fab. (The Apple Tree Flat Headed Borer), C. scitula 
and Agrillus anxious. 

tGill states that this difference is due to the fact that the adults emerge at any 
time from March to November, that is, that there is no definite period of a few 
weeks when they appear and lay eggs. U. S. D. A. Farmer's Bulletin, 843, p. 39 
(1917). 



29 

This insect works within the wood of the tree, attacking the 
trunk and the larger branches. It attacks trees which are appar- 
ently sound in every way. In ordinary infestations the damage 
done is not particularly serious, but the borers may eat out so much 
of the wood, in a young tree, as to cause it to break in a high wind. 

This species always leaves a hole through the bark at the be- 
ginning of its burrow. (Plate IX, fig. 3.) Through this hole it 
pushes out castings, rather large pellets of a yellowish, or fre- 
quently reddish color. These are very noticeable, at the foot of an 
infested tree, and through them attacks by this insect can always 
be located. 

The moths appear in the spring. The work of the larvae hatch- 
ing from their eggs is not apparent until the next fall, when the 
castings can be found under infested trees. The larvae feed till 
spring, then, after enlarging the entrance hole to their burrow, 
they pupate within it. When the moth emerges it leaves its empty 
pupal skin protruding from the burrow. It seems certain, at least 
in south Georgia, that there is one generation a year. 

CONTROL. 

This borer is easily controlled by injecting a little carbon bi- 
sulphide into the burrow and then plugging it with wax or even 
chewing gum. Some growers use a little medicine dropper for in- 
jecting the liquid, but one man who has had good success in con- 
trolling this insect uses a different method. He has his men carry 
with them a little vial of bi-sulphide, a small wad of cotton lint 
and a little ball of wax. This wax is made by melting together 
equal parts of beeswax and tallow. When thoroughly melted this 
is dropped into cold water and, as quickly as possible, is worked up 
into balls as big through as a quarter. Whenever a man sees evi- 
dences of borer work, he takes a bit of cotton, dips it into the bi- 
sulphide and pushes it into the burrow, after which he plugs the 
burrow with wax. 

This method has been mentioned at some length because of the 
fact that it shows the constant care and watchfulness exercised by 
this grower. With both cossids and flat-heads the most important 
point in control is watchfulness. Every time that evidences of their 



30 

presence are seen steps should be taken, immediately, to eradicate 
them. If this is done the grower will have little difficulty in con- 
trolling these pests. 

SHOT HOLE AND PIN HOLE BORERS. 

This group, following the general classification as made by 
growers, really includes several groups of insects which are quite 
widely separated in their characters, habits, etc. For all practical 
purposes, however, the grouping is perfectly sound. The presence 
of all these insects is evidenced by the smooth round holes which 
they leave in the bark of infested trees, these holes varying in size 
as indicated by the name of the group. Moreover, all these insects 
attack only such trees or portions of trees as are dead, dying or 
considerably weakened by other causes. They seldom do any ac- 
tual damage to a grove, being dangerous only through the fact 
that they may attack and kill a tree, which though in weakened 
condition might otherwise recover. 

The principal shot hole borer is known as the Red Shouldered 
Shot Hole Borer.* This insect caused considerable anxiety 
throughout south Georgia during the spring of 1917. The adult 
bores into a branch or even the trunk of a young tree, usually 
through, or just above a leaf scar. It then forms a circular tun- 
nel running partly, or entirely around the limb just within the 
woody portion. In this tunnel it lays its eggs, the young burrow- 
ing up the limb. (Plate IX, fig. 4.) These limbs are very easily 
snapped off at the location of the circular tunnel. 

As stated above, the work of this species was very abundant in 
1917, and at the time of its discovery the trees appeared to be in 
perfectly normal condition. Examination soon showed, however, 
that the infested trees suffered, invariably, from winter injury of 
so serious a nature that they must have died eventually from that 
cause alone, though at the time they had every outward appear- 
ance of perfect health. 

Another species of general occurrence during the same spring 
was the Pecan Ambrosia Beetle,t a little beetle which makes a hole 
less than one-thirty-second of an inch in diameter. This insect at- 

•Xylebiops (Sinoxylon) basilare Say. 
tXyleborinus (Xyleborus) pecanis Hopk. 



31 

tacks the trunk or branches, boring straight into them for a short 
distance and then turning up or down and following the general 
direction of the grain. It lays its eggs in a small chamber and the 
young borers, upon hatching, feed together in the egg chamber. 
This insect causes a greenish discoloration of the wood, especially 
about the egg chamber where the young larvae feed. As was the 
case with the shot hole borer, mentioned previously, the trees ap- 
peared to be perfectly sound, except for the work of these borers. 
Further examination, however, showed that they, too, were suf- 
fering from winter injury. 

While an attack by any of the various species forming this group 
is a certain sign that the host is in an unhealthy condition, such 
trees or portions of trees should always be removed and burned, 
for the general good of the grove. In addition to this all cut sur- 
faces, of any size, should be treated with a mixture of coal tar and 
creosote to prevent decay which will attract these beetles. This 
should be borne in mind particularly when top working trees. 

THE LESSER PECAN TREE BORER. 

(Synanthedon (Sesia) geliformis Walker.) 

Two different species of clear winged moths, both related to 
each other and to the peach tree borers, occur on pecan. One 
species has been recorded by Ilerrick* as attacking the pecan in 
Mississippi and this species appears to be the one attacking it in 
North Carolina. The moth is deep steel blue in color with yellow 
bands on abdomen and legs. Gossardf found a species attacking 
pecan in Florida and, not finding the adult, judged it to be the 
same insect. We have never taken this insect in Georgia, our form 
producing a moth which is dark brown in color, with a bright red 
hind body, or abdomen. It also seems probable that this is the 
species occurring in Florida. Since this form is related more 
closely to the Lesser Peach-tree Borer, and since moreover, the 
name Pecan Tree-borer has already been applied to the other spe- 
cies, it has seemed best to call our insect the Lesser Pecan-tree 
Borer. 



*(Sesla scitula Harris), Herrick, Glenn W., Miss. Agr. Exp. Sta., Bull. 86 (1804), 
p. 11. 

tGossard, H. A., Fla. Agr. Exp. Sta., Bull. 79 (1905), p. 299. 



32 

The life history of this species has not yet been thoroughly 
worked out. Moths appear over a period of at least three months 
in the spring, from the first of March to the last of May. They lay 
their eggs on the bark, and the young larvae, upon hatching, bur- 
row inward and commence feeding in the inner layer of bark. 
(Plate X, fig. 1.) The insects attack trees of all sizes and may be 
found anywhere from a foot above ground to 15 or 20 ft. above, 
in the branches. They spend the winter in the larval, or borer 
stage, pupating during the late winter or early spring. On 
emerging the moth leaves its empty pupal case protruding some- 
what, usually from beneath a scale of the bark. We have not been 
able to determine whether there are two generations a year or not. 
Since the lesser pecan-tree borers eat out only a small area, 
especially when compared to the size of the trees, they usually 
do not cause any material injury. Owing to the fact, however, 
that they appear to congregate mainly in a few trees they may some- 
times become so numerous as not only to seriously injure a tree but 
to girdle it, thus killing it outright. (Plate X, fig. 2.) 

CONTROL. 

No particular method of control can be recommended. The 
borers are worse on trees with rough scaly bark than on those whose 
bark is smooth. An occasional examination, through the winter, by 
removing rough pieces of bark, will usually reveal the work of these 
insects, if they are present, and the larva can be located and killed. 

Kepellant white washes have been tried to some extent but noth- 
ing of this nature has proven satisfactory thus far. 

A PECAN NUT CUECULIO.* 

Proliably the Walnut Curculio. 

(Conotrachelus juglandis Lee.) 

For several years reports reached this office of a weevil work- 
ing in pecan nuts and occasionally specimens of nuts with the 
characteristic weevil holes in them were sent in. These came from 
Putney, Ga., Thomasville and one or two places in north Georgia. 

*By C. S. Spooner. 



PLATE VIII. 




Fig. 1. Young tree, four years old, defoliated by web-worms. 




Pig. 2. 



Nearly mature nuts attacked 
by web-worms. 



PLATE IX. 




Fig. 



1. Twig girdler; egg punc- 
ture and scarring. 




Fig. 2. Twig girdler; egg. 
(Bark has been removed.) 




Fig. 8. Cossid Borer. Entrance 
to burrow. (Much reduced.) 



Pig. 4. Red shouldered Shot-Hole 
Borer. Entrance hole of adult, 
above bud, and channel made by 
young. 



PLATE X, 




Fig. 1. Lesser Pecan Tree Borer and work on tree 
(almost natural size). 




Fig. 2. 



Nine year old tree practically dead from work 
of Lesser Pecan Tree Borer. 



PLATE XL 




Pecan Phylloxera Galls on leaves. 



33 

Not until 1915, however, were these insects observed in any num- 
bers. 

In the spring of 1915 attention was called to a Hican tree at 
DeWitt, Ga., well loaded with nuts w-hich were attacked by a cur- 
culio. They showed the characteristic egg puncture with the cres- 
cent shaped slit below. Fully 90 ^/c of the nuts of this tree were 
attacked and fell. At the same time in other localities the same 
insect was observed working in the tender new shoots of pecan trees. 
In these cases the larvae were tunneling out the center of the shoot 
and caused its death. The probable reason for this difference in 
habit is that the Hican nuts are much earlier and larger than the 
pecans. They were large enough to support the young weevil larvae 
while the pecan nuts were not. Therefore on the pecans the in- 
sects had to deposit their eggs in the new sprouts. 

The full life history of this insect has not been worked out. Ac- 
cording to Mr. W. D. Pierce, of the U. S. Bureau of Entomology, an 
authority on this group, the insect probably has three broods a 
year in Georgia. Thus this insect can become a serious menace 
to the pecan industry. 

The larva of this insect when attacking the nuts eats out the 
inner part of the nut which soon falls to the ground. The grub then 
bores its way out and enters the ground where it forms a cell in the 
earth and pupates. 

Control measures have not been worked out yet, but shallow 
plowing at the time the weevils are in the ground in the pupal 
state is indicated. 

THE HICKORY AND PECAN WEEVIL. 

(Balaninus caryae Horn.) 

This insect has been reported as destructive to pecans, in Geor- 
gia, only during single widely separated seasons and from very lim- 
ited areas. As it might become of serious importance, however, it is 
well for the grower to know about it and to watch for it. 

The adult is a dark brown weevil, having a very long, slender 
snout. The young is a white grub, like that found in chestnuts. 
In fact this insect is very closely related to the chestnut weevil. 
The adult lays her egg in the nut, the grub hatching out and feed- 



34 

ing in the nut until fall, when it bores a round hole out through the 
shell, goes into the ground and pupates. The adults emerge during 
the spring or early summer. As will be seen, it is practically im- 
possible to tell whether an unopened nut has been attacked or not, 
unless the grub has left it. The egg puncture is so small that one 
can hardly find it. 

CONTROL. 

Probably the best method for controlling this pest is to fumi- 
gate the nuts with carbon bi-sulphide, using about 10 pounds to 
1,000 cubic feet. It is also reported that the grub may be killed 
by heating the nuts to 125^-150° Fahrenheit. With either method 
it is necessary to gather and treat all the nuts from trees which 
are found to be infested. They must also be gathered early, be- 
fore the grubs have entered the ground. 

One severe outbreak near Thomasville, Ga., was apparently 
controlled by turning hogs into the grove as early as possible in 
the fall. At least, no other control methods were tried and the in- 
sects did not cause any injury in the grove the following year. 

A LEAT FEEDING BEETLE.* 
(Diplotaxis excavata Leconte.) 

On April 16th, 1912, at DeWitt, Ga., a large number of leaves 
and young growing tips of pecans were found on the ground. These 
had been cut off by insects. For some time the cause of this trou- 
ble could not be located, but finally numbers of small holes were 
noticed in the ground. On examination these were found to con- 
tain a species of beetle known as Diplotaxis excavata. They are 
cylindrical black beetles a little less than half an inch long. They 
resemble somewhat the well known May bettles. The larvae live 
under ground on the roots of various plants and only the adult 
attacks the pecan. The injury was quite severe and had a decided 
pruning effect on the trees. The attack lasted about two weeks, 
when the beetles disappeared. 

If the beetles occur in sufficient numbers to seriously affect the 

*By C. S. Spooner. 



35 

trees they can be controlled by spraying at their first appearance 
with arsenate of lead at the rate of 3 pounds of paste, or 11/2 pounds 
of powder, to 50 gallons of water.* 

LEAF HOPPER, t 

(Empoasca sp.) 

Occasionally one notices that the leaves of pecans, especially 
the new tender ones, are very much curled and distorted. This is 
caused by small green sucking insects known as leaf-hoppers. They 
are very much like the apple leaf-hopper, bright green in color 
and about one-fourth of an inch in length. 

These insects feed on the under side of the leaf. They have 
mouth parts fitted for sucking and pierce the surface of the leaf 
with their beaks, sucking the juices of the plants. This causes the 
leaves to curl and when the insects are numerous seriously af- 
fects the nutrition of the tree, especially young trees with few 
leaves. 

These insects can be readily controlled by a spray of whale 
oil soap, one pound to two gallons of water. As this insecticide 
kills by contact and not by being eaten care must be taken to 
hit the under side of the leaves where the insects stay. 



PECAN PHYLLOXERA. 

(Phylloxera sp.) 

The pecan phylloxera is a small plant louse which causes the 
formation of galls on the leaves and leaf stems. (Plate XI, fig. 1.) 
It is seldom found on old trees, but occurs quite frequently on young 
ones and is very common on nursery stock. It apparently does no 
damage in particular and up to the present no measures of control 
have been needed against it. 



*At least one species of the true May beetle may cause serious Injury of a 
somewhat similar nature. Such an attack was observed near Augusta, In 1917, the 
trees being almost entirely defoliated. (W. F. T.) 

tBy C. S. Spooner. 



36 

THE PEQAN APHIS. 

(Monellia costalis F.) 

This is the small yellow species with the front margins of the 
fore wings bordered with dark brown or black, which occurs on 
pecans throughout south Georgia. It is accompanied by a second, 
somewhat smaller species* of much less common occurrence which 
lacks the broad, dark wing margin. This second species carries its 
wings over itself like a roof while the commoner species holds them 
flat over its back. 

The aphids may first be found, in the spring, about the last of 
March, at Thomasville. When full grown these insects are winged 
and only females occur. From then on, throughout the summer 
and early fall, generation follows generation, all adults being fe- 
males and bearing living young (parthenogenetic and viviparous). 
Also they are all winged. There may be as many as twenty-one 
such generations during a season, each female producing about thir- 
ty to forty young on the average. We have a record of one which 
bore 239 young. 

About the middle of October young aphids are found which dif- 
fer somewhat in color and markings and in general appearance 
from the others. These eventually grow into egg laying (oviparous) 
females and males.. These females are without wings (apterous) 
even when fully grown. The males are winged but are somewhat 
smaller than the summer form and bear black markings on the 
thorax, by which they may easily be determined. 

These males and females mate and the latter lay small eggs, de- 
positing them on the trunk and main branches, under loose bark. 
This egg stage carries the insects over winter, the eggs hatching 
the following March to start another year's cycle. 

Both species feed on the under surface of the leaves, appar- 
ently preferring rather old foliage to the newer and more tender 
growth. The insects with flat wings, and their young, are found 
well scattered about over the leaves, while adults of the other spe- 
cies are usually to be found surrounded by several young, all rather 
close together. This seems to be due to the fact that the flat winged 
species is more "nervous" than the other, not remaining in one 
'Monellia sp. ' 



37 

place as long and being much more prone to jump when disturbed 
in any way. 

These species do not appear to cause any serious damage, at 
present. For one thing, although they reproduce so rapidly, quan- 
tities of them are destroyed by lady beetles and their young, which 
swarm over the infested trees. In case of a severe outbreak the 
trees should be sprayed with a nicotine solution and soap. 

SPITTLE INSECT. 

During 1917 this insect, whose young live within small accumu- 
lations of a froth-like material, was very abundant on pecans in 
some localities, especially about Thomasville and Valdosta, and was 
the cause of many inquiries from growers in these districts. 

, In the spring the young feed mainly on the swollen bases of the 
leaf stems. Later they attack the young nuts and it is on these 
that they are usually to be found during the summer and early 
fall. It is this habit which caused anxiety among the nut growers. 
Numerous observations and experiments have failed, thus far, to 
show any particular evidence of injury by this species. In our ex- 
periments, nuts fed on by the insects were no more liable to fall than 
were those which were free from attack. Consequently, the pres- 
ence of this species need not cause any uneasiness and no control 
measures are needed. 



38 
PECAN SCAB. 

{Fusicladium effusum.) 

BY C. S. SPOONEE. 

Pecan scab is the most serious disease affecting the pecan. It 
is caused by a fungus which enters the tissues of the leaves and nuts 
and seriously affects their development. Its presence may be recog- 
nized by small black pustules on the surface of both leaves and 
nuts. The pustules are about 1-18 of an inch in diameter and may 
be so numerous as to practically cover the entire surface. The pus- 
tules contain the spores of the fungus and it is by means of these 
spores that the disease is spread. They escape from the pustules 
and lodge upon fresh surfaces where, in the presence of moisture 
they germinate, enter the tissue and develop into the fungus which 
in turn develops new pustules and spores. 

"When the disease is confined to the leaves it does not seriously 
affect the health of the tree, but when it attacks the nuts it does 
affect the development of the nut. It causes the nut to drop off 
or reduces its size according to the abundance of the fungus. 

Susceptible and Immune Varieties. 

There is a great difference in the susceptibility of the different 
varieties of pecans to scab. Some are apparently entirely im- 
mune, others are attacked very slightly, showing scab spots on a 
few nuts which are growing close to the trunk or heavily shaded by 
the branches, while others are very severely attacked so that few if 
any nuts escape injury. This is strikingly shown by trees of dif- 
ferent varieties growing next one another. On one the whole crop 
will be diseased, while on the other no trace of the disease will be 
found. There is also apparently a sectional difference in the de-. 
gree of susceptibility to scab. For example, in the Thomasville dis- 
trict the Delmas scabs badly ; while in the Albany district it is quite 
free from disease. In Florida the Van Deman is reported as scab- 
bing badly, while with us it is only slightly affected. 

The varieties which are most subject to scab with us are, Geor- 
gia, San Saba and other Texas varieties, Capitol, Delmas and many 
seedlings. Seedlings are usually very severely injured by scab. 



39 

Van Deman, Schley, Alley, Halkert, Mobile scab to a slight de- 
gree, but not enough to warrant uneasiness. Scab has also been re- 
corded as occurring on Stuart and Jewett to a slight extent. 

Present indications show that Money-maker, Russell, Stuart, 
Schley and Alley are among the better known varieties which are 
safe to plant from the standpoint of scab. 

Seasonal Difference. 

There is a great seasonal difference in the severity of scab. Very 
wet seasons promote the growth of the fungus to a great degree. 
One season has been observed by the writer in which practically 
every Georgia nut in one grove was destroyed by scab before the 
season was half over. 

On the other hand in very dry seasons the loss is hardly notice- 
able, when the nuts are so lightly attacked that the greatest injury 
is shown by the presence of many under-sized nuts. Between these 
two extremes the amount of damage will vary according to the 
season. 

Bemedial Measures. 
The aim in spraying for Fungus Diseases. 

In discussing control measures, the underlying principle of 
spraying for fungus diseases of plants should be remembered. The 
fungus is spread through the air by means of very minute spores. 
These lodge on leaves and nuts and there remain dormant until they 
come in contact with moisture. Thus after a rain, when the leaves 
are still wet the spores germinate and send a small thread into the 
tissue of the plant. The fungus then develops rapidly. 

The object of the spraying is to have the poison on the leaves 
when the moisture comes so that the presence of the poison in the 
water will kill the spore before it has time to germinate. There- 
fore a spray applied before a rain is infinitely more effective than 
one applied afterwards. 

The Choice of a Fungicide. 

A fungicide is a chemical combination applied to a plant for 
the purpose of controlling or destroying fungi which attack the 



40 

plant. There are several fungicides which give excellent results 
in combating other fungus diseases and several of these were tried 
on pecans to determine which was the most effective against the 
scab. 

Atomic sulphur was applied on one block of trees at the rate of 
seven pounds to fifty gallons of water and to another block at the 
rate of five pounds to fifty gallons of water. No beneficial results 
whatever were observed. 

Lime sulphur (Commercial) was used at the strength of one gal- 
lon to thirty gallons of water and one gallon to fifty gallons of 
water. Both of these strengths burned the foliage quite severely 
and did not control the disease. Some slight benefit was noticed, 
but because of the severe burning this fungicide was abandoned. 

A winter spray of lime sulphur at the strength of one gallon 
to ten of water, was applied January 22nd. No benefit was seen 
from this treatment. The trees which had received this treatment 
together with some which had not received it were later sprayed 
with Bordeaux Mixture. No difference in the results was ob- 
tained on the two blocks. 

Bordeaux Mixture was used at strengths of 3-3-50 and 5-5-50. 
The results with the two strengths did not differ so that the 3-3-50 
formula was used. This fungicide was used in many experiments. 
A differing number of sprays was applied and in many cases good 
results were obtained. Following is a summary of the experiments : 

In 1912 Bordeaux was used on only one tree. Most of the work 
of this year was confined to atomic sulphur and lime sulphur. As 
shown above, these two fungicides were unsatisfactory and were 
abandoned. The one tree sprayed with Bordeaux gave some evi- 
dence in favor of this fungicide and it was tried extensively in 
1913-1914. 

The experiments in 1913 were carried out with Bordeaux Mix- 
ture at the strength of 3-3-50. The trees were divided into five 
blocks and treated as follows: Block C was left unsprayed as a 
check on the other blocks. Block A was sprayed April 18th and 
June 3rd. Plot D sprayed March 17th, April 18th and July 16th. 
Plot E sprayed March 17th, April 18th, June 3rd and July 16th. 
Plot F sprayed April 18th, June 3rd, July 16th. 

In getting the following percentage the drops which showed 



PLATE XII. 



WMM 


■| 






■[ 


■ 


Hi 


^H 


H 




^vJ^^H 


1 


i 


9 


^^p 


Hi 


^F 




H 


1 


Ih 


^^^^^^^Ki -."'' 


""^-\r~ 


N 


^^'— -^^As^^B 


^1 


w 




^v' 




^°^ 




^K 




'^^: 


^^^^^^^^^Hr< 




^sS&^ 




^^^^^^^K^ 




V^BgK 


1 


^/ 


4-- 


ji^^^^H 


1 


i 


J 



o 
o 

2c 



ci3 
<BrH 

>> 

^ bii 
f/fe 



« 

60 

s 




bo 
C to 



roc 

r? CO 
0*i 



PLATE XIII. 




Fig. 1. Diseased kernels, showing appearance of Kernel Spot. 




Pig. 2. Brown Leaf Spot. Moderately severe infestation. 



PLATE XIV. 




Pecan scab (Fusicladium effusum). 



PLATE XV. 




Spraying pecan trees with gasoline sprayer (using tower). 



41 

scab supposedly would have matured if it had net been for the 
scab, so that these together with the matured nuts were taken as the 
normal crop. A careful count was kept of all drops and those 
showing scab were counted separately. The number of the drops 
showing scab divided by the total crop would give the percentage 
of the crop affected by scab. 

In Plot C, unsprayed, 72% of the crop dropped be- 
cause of the scab. 

Plot A, two sprayings April 18th and June 3rd, lost 
15% of the crop. 

Plot D, sprayed March 17th, April 18th, July 16th, 
lost 29% of the crop. 

Plot E, sprayed March 17th, April 18th, June 3rd, 
July 16th, lost 20% of the crop. 
Plot F, sprayed April 18th, June 3rd, July 16th, 
lost 24% of the crop. 

It will be seen that all of the sprayed plots showed a distinct 
improvement over the unsprayed. The plots varied somewhat in un- 
expected ways, as is shown by Plot A having a better percentage 
than Plot E, although the latter had two more sprayings. I'his was 
caused partly by the variations in the size of the crop on different 
trees and other factors which could not be controlled. It also shows 
that the two sprays, applied April 18th and June 3rd, were the 
most essential ones in the control of the scab. There can be no 
question but what it paid to spray these trees. 

The year 1914 was very dry and while extensive spraying experi- 
ments were carried on the results are very hard, if not impossible, 
to tabulate. The scab showed up very late in the season, July 11th 
being the date when it was first observed and then very little of it 
was found. For this reason the damage to nuts, sprayed or un- 
sprayed, was very slight. No difference could be found in the 
niunber of drops caused by scab because there were so few of them 
either on the sprayed or unsprayed trees. 

A very decided difference could be observed while the nuts 
were on the trees, however. On the sprayed trees the nuts showed 
much less scab than those on the unsprayed trees and they ran 
larger and better. While these experiments did not materially im- 
pi'ove the crop they showed again that Bordeaux would control the 
scab to a great extent. They showed no material benefit because 



42 

tJhe season was so dry that spraying for this disease was not nec- 
essary. 

It will be seen from the above experiments that while no com- 
plete control was effected, a very considerable amount of good was 
accomplished by the spraying, especially in 1913, which was a fairly 
wet season. An increased number of sprayings in wet seasons 
would unquestionably give greater control. 

No set rule can be given as to the dates of spraying. Each sea- 
son will be different. The grower must be governed by the amount 
of rainfall each year. It is well to apply a coat of the spray soon 
after the nuts are formed. Subsequent sprayings can then be de- 
termined later. The trees need not be sprayed during a long, dry 
spell, but in wet weather spray every ten days or two weeks. 

Too much emphasis cannot be laid on the necessity for thorough 
spraying. A careless, hit or miss application costs as much to apply 
and uses as much material as a good, thorough job and the results 
are widely different. In many cases where statements are made to 
the effect that spraying did not control the disease it can be shown 
that the spraying was not carefully done. 

Be sure to hit every leaf. If necessary it will be worth the 
time of a reliable man to go with the spraying outfit to see that the 
spray is properly applied. 

Preparation of Bordeaux Mixture. 

Bordeaux Mixture must be properly made to be effective. It 
will therefore be Avell to give instructions for those who are unfa- 
miliar with this Mixture. Bordeaux Mixture is made from copper 
sulphate, lime and water. The formula 3-3-50 means that three 
pounds of copper sulphate and three pounds of lime are used to fifty 
gallons of water. Each ingredient should be mixed separately with 
a little water and then each is poured in a separate barrel and 
enough more water added to make twenty-five gallons of each solu- 
tion. These are then poured together into the spray tank. Barrels 
placed on a platform and connected up as shown in the figure make a 
most convenient outfit for mixing Bordeaux. 

The lime should be unslacked. If old air slacked lime is used 
the resulting mixture is liable to seriously burn the foliage. Hy- 



43 

drated lime, if readily obtainable, is the most convenient to use as 
it is more easily suspended in the water. 

If much of the solution is to be used it will be found best to tie 
the required amount of copper sulphate in a sack and suspend the 
sack near the top of a barrel of water. This should be done the 
evening before spraying. It will have all dissolved by morn- 
ing. The required amount can then be dipped out as needed. 

Top Working to Immune Varieties. 

The- question is often asked if it would not be best to top work 
scabbing varieties with, immune varieties. In young groves this is 
undoubtedly the best thing to do. Of course, it is not policy to 
plant scabbing varieties in groves. However, in large, bearing 
groves each grower must decide for himself, whether he 
would prefer to spray or to top work his trees with the resulting 
curtailment of his crop for several years. As to the expense con- 
cerned, it is a question which is better. Over a long term of years, 
the top-working, if successfully done, would be the cheaper. . 



44 
PECAN DISEASES OTHER THAN SCAB. 

BY C. G. CRITTENDEN.* 
PECAN ROSETTE. 

IMPORTANCE AND SYMPTOMS. 

Pecan rosette is considered by growers of pecans, to be one of 
the most serious diseases with which they have to contend. It 
makes its first appearance in a tree through the putting out of 
mottled yellow leaves which are usually more or less wrinkled and 
undersized. It may appear over the whole tree at once, but often 
affects one branch long before it shows up in the rest of the tree. 
The affected branches are stunted and fail to grow the usual length. 
This shortens the distance between the leaves and thus forms a "ro- 
sette." A tree lightly affected one season may not show the dis- 
ease the next season. However, trees badly affected seldom re- 
cover. If a tree is badly affected the branches usually die back from 
the tips, either the first season or later. In some cases, this dying 
back may go so far as to kill the tree. More often, however, it 
does -not go that far. In the spring new branches come out at the 
base of the dead branch, and these in turn die back, so that the 
final result in the case of a tree badly rosetted for years, is a 
gnarled unsightly dwarf. (Plate XII, figs. 1 and 2.) 

NATURE OF THE DISEASE. 

Rosette is neither a fungus nor a bacterial disease, but is what 
is termed a physiological disease and is, probably, the result of 
some defect in nutrition. Orton and Randt have shown that it is 
due to some unfavorable condition of the soil. "When they trans- 
planted trees into holes from which rosetted trees had been re- 
moved, a large proportion of these healthy trees became rosetted 
and if the transplant was reversed and rosetted trees were planted 
in places from which healthy ones had been removed, a large propor- 
tion of these diseased trees recovered. These investigators also 
found that budding or grafting healthy buds or scions on rosetted 
stocks gave rosette in the scion and conversely that working buds 
or scions from rosetted trees onto healthy stocks produced healthy 
trees. 



'Formerly pathologist with the Georgia State Board of EntomologJ^ 
tOrton, W. A., and Rand, F. V. Pecan Rosette. Jour. Agr. Res. vol. 3, No. 
2: pp. 149-174, 1914. 



45 

The disease is non-parasitic and noninfectious and is the result 
of some unfavorable condition in the soil. 

CONTROL. 

No method for curing rosetted trees can be recommended. 
Trees which are badly diseased should be removed and replaced by 
healthy trees. Many of these healthy trees are likely to become 
rosetted, but some can be depended upon to remain healthy, others 
will not be as badly affected as those removed, while some, prob- 
ably, will be as bad as the old trees. 

All rosetted nursery stock should be discarded and only thor- 
oughly sound stocks used for budding or grafting. 

In selecting a location for a grove, choose a good fertile soil 
with a clay subsoil. Avoid a sandy subsoil and do not plant a 
pecan tree where no other crcp -,vill succeed. 

BEOWN LEAP SPOT. 

{Cercospora fusca Rand.) 

The brown leaf spot is the most prevalent and most conspicuous 
leaf disease of the pecan. It probably occurs wherever the pecan is 
grown. The loss occasioned by the disease is difficult to estimate, 
as only the leaves are affected. In severe cases there may be con- 
siderable defoliation of the trees. 

Different varieties of pecan show little or no difference in sus- 
ceptibility to the disease. 

SYMPTOMS. 

The disease first makes its appearance on a leaf as a small dark 
brown irregular spot with an indefinite outline, which extends 
through the leaf and is visible on both surfaces. There may be 
many of these on one leaf. The spot increases in size and often 
reaches a half inch in diameter, and the larger ones sometimes become 
light broAvn in the center. (Plate XIII, fig. 2.) 

CAUSE OF THE DISEASE. 

Brown leaf spot is caused by a fungus, the threads of which 
penetrate the leaf. When the spots are from five to six weeks 



46 

old, club-shaped spores of the fungus are produced, usually on their 
upper surface. These spores may be carried by wind to other 
leaves where they produce new spots. First infections appear in 
early summer and the disease continues to spread throughout the 
summer and till fall. 

CONTROL. 

The disease is usually not severe enough to make it profita- 
ble to attempt to control it. It may be prevented by thoroughly 
spraying the trees three times with Bordeaux mixture. The first 
spray should be applied soon after the trees are fully leaved out. 
The second and third should follow at intervals of three to four 
weeks. 

KERNEL SPOT. 

(Coniothyrium earyogeniim Eand.) 

Up to the present time this disease has been given little consid- 
eration, either by pecan growers or by workers on pecan diseases. 
The loss occasioned by the disease has hitherto been small, only 
occasionally on a single tree or in small groves here and there has it 
been reported serious. However, the disease appears to be spread- 
ing and the damage increasing. During the season of 1916, se- 
rious loss was inflicted on some growers in the vicinity of Thomas- 
ville and Cairo. One Thomasville grower sold his crop of Schleys, 
which were damaged by kernel spot, for 25 cents per pound when 
prices for good Schleys ranged from 50 to 60 cents. 

SYMPTOMS. 

As the name implies, the disease affects only the kernel'. It can 
be detected only after the shell is removed. The spot on the ker- 
nel is irregular in outline, dark brown or black and usually some- 
what sunken. It is about 14 to % inch in diameter. (Plate XIII, 
fig. 1.) 

When the kernel is cut the brown diseased area is found to ex- 
tend into the meat to a depth of perhaps % of an inch. The dis- 
eased spot is bitter and imparts a bitter flavor to the rest of the 
meat. 



CAUSE OF THE DISEASE,* 

Kernel spot is caused by a fungus. This has been proven by 
Rand, of the U. S. Department of Agriculture. The life history of 
the fungus is not very well known. As far as is at present known 
it affects only the kernel. When an affected kernel is placed un- 
der moist conditions pycnidia or spore bearing bodies are formed 
by the fungus. Inside the pycnidia are produced the spores which 
are the means of reproducing the disease. At what time or just 
how infection of the kernel takes place is not known. 

CONTROL OF THE DISEASE. 

No efforts have thus far been made to control the disease and 
no specific method can be given at this time. However, there are 
certain measures which can be recommended as giving promise. - As 
previously stated, so far as is known, the disease affects only the 
kernel of the nut. If this is true then removal from the orchard or 
destruction of all nuts in the fall should reduce the amount of dis- 
ease the following year. 

Some varieties seem to be more susceptible to the disease than 
others. The Schley appears to be most seriously affected and Suc- 
cess and Curtis are probably more susceptible than others. 

OTHER DISEASES OF PECAN. 

NURSERY BLIGHT. 

(Phyllosticta caryae Peck.) 

This is a fungus disease which is confined almost entirely to the 
nursery, where it often does considerable damage. Only the leaves 
are aft'ected. ' ' Generally the first indications of infection appear 
in the form of minute roundish spots which are dark reddish brown 
on the upper surface and blackish on the lower. These slowly in- 
crease in size until a diameter of 2 to 5 mm. (^-^2 ^^■) is often 
reached in the individual spots. "With increase in size the center 
of the spot on the upper surface assumes an ashen gray color, 

*Investigations conducted during the season of 1917 seem to indicate that the 
Green Soldier Bug (Nezara hilaris) is a very important factor in the production 
of this disease. We have not been able to determine, absolutely, whether the spot 
is caused by a fungus which is carried by the bug, or whether the spot is directly 
due to the feeding of the bug. This bug is the insect frequently called a "pump- 
kin bug" which occurs very commonly on cow peas. (William P. Turner.) 



48 

which is usually bordered with reddish brown, while the lower sur- 
face remains black throughout or with an occasional tiny ashen- 
gray spot in the center of this dark colored area."* 

CONTROL. 

Spray with Bordeaux mixture four times. Begin spraying as 

soon as the trees are fully leaved out and repeat at intervals of 

three to four weeks. 

ANTHRACNOSE, 

{Glomerella cingulata (stonem) S. V. & S.) 

This disease affects both the leaves and the nuts. The af- 
fected spots on the leaves are irregular in outline and grayish brown. 
They vary in size and sometimes cover a whole leaf. Leaves badly 
affected usually fall to the ground. On the nuts the disease pro- 
duces black sunken spots which are irregular in outline and 
sometimes causes a heavy drop of half grown nuts. The dis- 
ease is caused by a fungus. No method of control can be given at 
the present time. 

CROWN GALL. 

{Bacterium tumefaciens (S. M. & Town.) 

This disease is rare on the pecan. "When present it produces 
swellings or galls ®n the tree trunk below the surface of the 
ground. It is produced by the same bacteria which causes crown 
gall of the peach, apple, etc. 

» 

CONTROL. 

All nursery trees found to be affected with crown gall should 
be discarded and destroyed. 

MILDEW. 

(Microsphaera alni (Wallr) Wint.) 

Mildew is more or less common on the leaves and nuts of the 
pecan, occurring most often on the lower shaded branches of the 
tree. .It produces a white poAvdery covering often involving the 
whole surface of a nut. The mildew produces little or no damage 
and can be ignored. 

♦Rand, F. V. Some diseases of pecans. Jour. Agr. Res. 11, No. 4: pp. 303-S37, 

T914. 



LIST OF AVAILABLE PUBLICATIONS, 
GEORGIA STATE BOARD OF ENTOMOLOGY. 

Bulletin No. 12— The Mexican Cotton Boll Weevil, 1904. 

Bulletin No. 13 — Some Common Insects Injurious to the Apple, 1904. 

Bulletin No. 26— Peach Leaf Curl, Yellows, Eosette and Little Peach, 1908. 

Bulletin No. 34 — Wilt Disease of Cotton in Georgia and Its Control, 1911. 

Bulletin No. 37 — Crop Pest Law of Georgia, Other States and Canada, 1912. 

Bulletin No. 39— The Mexican Cotton Boll Weevil, 1914. 

Bulletin No. 40— Cotton Wilt in Georgia, 1915. 

Bulletin No. 41 — Some of the More Important Truck Crop Pests in Georgia, 

1915. 
Bulletin No. 42 — Annual Report of the State Entomologist for 1914. 
Bulletin No. 43— The Principal Parasites of the Peach, 1916. 
Bulletin No. 44— The Mexican Cotton Boll Weevil, 1916. 
Bulletin No. 4.5 — Annual Report of the State Entomologist for 1915. 
Bulletin No. 46 — Cotton Variety Tests for Boll- Weevil and Wilt Conditions, 

1916. 
Bulletin No. 47 — How to Grow Cotton in Spite of Boll-Weevil. 
Bulletin No. 48 — Annual Report of the State Entomologist for 1916. 
Bulletin No. 49 — Pecan Insects and Diseases. 
Bulletin No. 50— Cotton Variety Tests, 1917. 
Bulletin No. 51 — Annual Report of the State Entomologist for 1917. (In 

preparation.) 
Circular No. 6 — The Use of Soluble Oils Against San Jose Scale, 1907. 
Circular No. 7 — The Hessian Fly in Georgia, 1908. 

Circular No. 8 — Experiments for Control of San Jose Scale, 1907-1908. 
Circular No. 9— The Brown-Tail Moth, 1909. 

Circular No. 11 — Wilt Diseases of Cotton and Its Control, With Suggestions 
on Seed Selection. 

Circular No. 19 — Boll-AVeevil Quarantine Regulations, 1906. 

Circular No. 20 — General Instructions for Making First-Year Cotton Selections. 

Circular No. 21 — Experimental Dusting and Spraying of Peaches. 

Circular No. 22 — Control of Insects Attacking Stored Products. 

Circular No. 23 — Boll Weevil Quarantine Regulations, 1917. 

Circular No. 24 — Helpful Hints on Dusting Peaches. 

Circular No. 25- — Boll Weevil Quarantine Regulations, 1918. 




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